A vertical alignment (VA) display device is widely used due to the advantages of high contrast ratio, wide viewing angle, and the like. Generally, the VA display device comprises an array substrate and a color filter substrate. Gate lines and data lines arranged in a staggered manner with respect to each other and sub-pixel units formed by the gate lines and the data lines are disposed on the array substrate. Color filter corresponding to the sub-pixel units, and black matrix corresponding to the gate lines and the data lines, are formed on the color filter substrate. The array substrate and the color filter substrate are assembled together, and liquid crystal molecules are packaged therein, thereby a liquid crystal panel of the display device is formed. An electric field is formed between the array substrate and the color filter substrate. The liquid crystal molecules are controlled to deflect through adjusting the intensity of the electric field, so that the intensity of light passing through the liquid crystal molecule layer can be changed. Light with different intensities coordinates with the color filter on the color filter substrate, so that the display device can display color images.
Since the array substrate and the color substrate are fixed together through a frame around all four sides thereof, relative shift would easily occur to a display region. Due to the relative shift, the black matrix of the color filter substrate may fail to effectively cover light-leaking regions around the data lines of the array substrate. As a result, an undesirable display defect of “light-leakage on a black image which is in a vertical direction of a bright image” would occur. Generally, this undesirable display effect is named as vertical crosstalk (V-crosstalk).
Specifically, the principle of V-crosstalk caused by the relative shift between the array substrate and the color filter substrate of the liquid crystal panel is as shown in FIGS. 1-5. FIG. 1 schematically shows a structure of a sub-pixel unit 1 of an array substrate formed through a five-time patterning process. When a data signal transmitted through a data line 4 of the sub-pixel unit 1 is low bias voltage all the time (as shown in FIG. 2), liquid crystals on both sides of the data line 4 will not deflect (as shown in FIG. 3), and therefore the light-leaking regions will not be formed. When the data signal transmitted through the data line 4 is alternately high bias voltage and low bias voltage (as shown in FIG. 4), the liquid crystals on both sides of the entire data line 4 will deflect in the case that the signal transmitted through the data line 4 is high bias voltage, thereby forming light-leaking regions (as shown in FIG. 5).
Under ideal conditions, in order to realize a maximum aperture ratio of the sub-pixel unit 1 (namely the ratio of an area of an aperture region, which permits light to pass through, to that of the entire sub-pixel unit 1), it is expected that a black matrix 5 can block exactly to an edge of a pixel electrode 9 of the sub-pixel unit 1 (as shown in FIG. 6). However, in order to avoid V-crosstalk, the black matrix 5 is usually widened, so that it further extends towards a center of the pixel electrode 9 for a distance X1 (as shown in FIG. 7). The value of X1 depends on the degree of the relative shift between the array substrate and the color filter substrate, and the degree of the relative shift depends on specific conditions of the liquid crystal panel comprising the array substrate and the color filter substrate. The degree of the relative shift is usually in a range of 0-30 micrometers. The higher the degree of the relative shift is, the higher the probability of V-crosstalk. Generally, the value of X1 is in a range of 2-20 micrometers, and the higher the value of X1 is, the larger loss of the aperture ratio. However, with respect to an ordinary sub-pixel unit 1 (as shown in FIG. 8), since data lines 4 are arranged on both sides of the pixel electrode 9, the area loss of an aperture region in each sub-pixel unit is 2×X1×H1 (H1 is an effective height of the aperture region), thereby causing large loss of aperture ratio. Consequently, the display effect and the light emergent effect of the display device will be influenced.